Solve the Problem $y = 1 - \frac { x ^ { 2 } } { 4 }$

Multiple Choice

Solve the problem.
-An auxiliary fuel tank for a helicopter is shaped like the surface generated by revolving the curve $y = 1 - \frac { x ^ { 2 } } { 4 }$ , $- 2$ $\leq x \leq 2$ , about the $x$ -axis (dimensions are in feet) . If a cubic foot holds $7.481$ gallons and the helicopter gets 3 miles to the gallon, how many additional miles will the helicopter be able to fly once the tank is installed (to the nearest mile) ?

A) 38
B) 150
C) 75
D) 50